"Some of their judges aren't even singers and wouldn't be able to sing a note, so what do they know?" he told The People. "Every time I see one of these shows I think half the decisions are wrong and it really frustrates me.

"Some of the judges don't have the experience to be on talent shows - if you've only been in the industry two minutes, how can you offer advice?

"I have the experience and I listen to all sorts of music, so the advice I give will be valuable."

Jones said that it was his disappointment in the poor judging decisions and "sob stories" of The X Factor that inspired him to join The Voice.

"You are basically talking about worldwide success for nearly all of the stars who've come through the ranks on Simon's shows," a source said. "It's a bit rich for someone appearing as a judge on a BBC show that hasn't even started yet to criticise him.

"Simon's always held Tom Jones in high regard but he's being drawn into a PR stunt by the BBC when he should know better."